Tooth Shade Clinical Trial
Official title:
Assessment of Tooth Shade After De- and Re-Hydration During Clinical Restorative Procedures (A Randomized Clinical Trial)
The aim of this study was to investigate any change in tooth color resulting from dehydration resulted from rubber dam application and the time required for any change to return to baseline and to investigate the nature of change and areas of the teeth most affected.
Architecturally speaking, a smile comprises 60% of the weight of our face. Subconsciously, a
smile has a visual impact on people appearance. Also statistically reveal that people place a
high value on their smiles according to the American academy of cosmetic dentistry survey
(AACD)2017. As the population becomes increasingly aware of the role teeth play in
appearance, patients' expectations of aesthetics in contemporary dentistry are ever
increasing. So practicing esthetic dentistry that is defined as reproducing natural looking
teeth by creating perfect esthetic restorations has been for long time a strict challenge due
to many materials' limitations impacting either shade integration or surface quality, and
possibly colour stability.
Tooth colour was the main reason for patient dissatisfaction in a survey concerned with
esthetic appearance.(1) Thus accurate shade measurement together with proper communication of
tooth colour is integral to a successful aesthetic outcome.(2) It is compulsory that
clinicians understand the light interaction with tooth structures as well as the proper
histo-anatomic principles for a better material and shade selection during direct and
indirect restorative procedures. Tooth structures form a complex optical medium for light as
it passes through enamel, dentino-enamel complex and dentin in terms of gradient between
transparency (complete transmission of light) and opacification (complete reflection of
light).(3)Furthermore, this behavior changes over the years, as tissues change in morphology
and composition. Comprehension of dynamic aging of tooth structures is a key for success when
selecting the proper value and chromaticity for restorative materials.(4,5) Thus clinicians
and technicians should have sufficient training in tooth shade selection. For achieving
excellent esthetic outcomes there are four main contributing variables: Dynamic Light
Interaction, Histo-anatomical Features, Smilography and the 9 Elements of visual
synthesis.(3) In the modern dental practice, restoring the optical features of the intact
tooth presents a challenging task, due to the inherent translucent nature of enamel, the
dentinoenamel complex (DEC) and dentin. Translucent materials offer a significant color
measurement challenge since they interact with light in a far more complex manner than most
other materials. The old traditional visual estimation approaches that solely employ the
Munsell color model system based on hue, chroma, and value (H/C/V) dominating the dental
market appear to be insufficient when assigning the relevant information among the dental
team members (clinician/technician/patient).(6) In 1931 The Commission Internationale de
l'Eclairage (CIE) defined a standard light source, developed a standard observer and enabled
the calculation of tri-stimulus x, y, z values, which represent how the human visual system
responds to a given colour and allows us to transform spectral energy data into meaningful
colour data. It should be noted that the DE in the L*a*b* colour space indicates the degree
of colour difference not the direction of the colour difference. It is frequently interpreted
in dental literature that a DE of 1 is the 50:50 perceptibility threshold. The hues of
natural teeth tend to be in the yellow to yelloworange range, determined mainly by the colour
of dentine, with enamel playing only a minor role through scattering at wavelengths in the
blue range.(7) Instruments for clinical shade matching include spectrophotometers,
colourimeters and digital imaging systems.(8) It has been reported that VITA Easyshade has to
be the most reliable instrument in both in vitro and in vivo circumstances.(2) It has been
reported that dehydration of teeth can make them appear whiter by increasing enamel opacity
when examined by The Easyshade as the light can no longer scatter from hydroxyapatite crystal
to crystal.(6,10,11)The resulted loss of translucency on dehydration therefore causes more
reflection masking the color of the underlying dentine and thus appears lighter. Russell et
al.(12) applied a rubber dam to the anterior teeth of seven subjects and allowed the teeth to
dehydrate for 15 min that was measured using a spectrophotometer and further three
spectrophotometric measurements were taken at 10 min intervals after removal of rubber dam
and tooth rehydration. It was noticed that tooth colour had become lighter and less saturated
after dehydration and the colour of the teeth returned to their baseline values 20 min after
removal of the rubber dam. Most dental procedures cause some dehydration of teeth.(13-16) It
is recommended to record the shade of teeth at the begining of the appointment but there is
insufficient evidence in the dental literature to support it.(14) Color mismatch between
restoration and natural teeth is a common complaint resulting in remake of restorations and
increased expense.(2) As most dental procedures lead to dehydration of teeth which can alter
their shade and may lead to errors in shade matching. And in order to avoid unacceptable
mismatch of color between natural teeth and dental restoration, it is important that the
shade matching procedure is carried out at the beginning of the appointment. Thus the aim of
this study was to investigate any change in tooth color resulting from dehydration resulted
from rubber dam application and the time required for any change to return to baseline and to
investigate the nature of change and areas of the teeth most affected.
;